This invention relates to X-ray diffraction systems. X-ray diffraction is a non-destructive technique for the qualitative and quantitative analysis of crystalline material samples, which are generally provided in the form of powders or solids. In accordance with this technique, an X-ray beam is generated by an X-ray tube with a stationary anode, by a conventional rotating anode X-ray source or by a synchrotron source and directed toward the material sample under investigation. When the X-rays strike the sample, they are diffracted according to the atomic structure of the sample.
X-ray diffraction data can be collected using one-dimensional diffraction (1D) profiles and two-dimensional (2D) profiles. One dimensional profiles are measured by rotating the sample and detecting diffracted X-rays with scanning point detectors or linear position-sensitive detectors. Two-dimensional profiles are acquired with two-dimensional, or area, detectors and the resulting data is then processed using two-dimensional image processing and two-dimensional diffraction pattern manipulation and interpretation. A typical two-dimensional laboratory diffractometer system 100 normally consists of five components as shown in FIG. 1. The components include an X-ray source 102 that produces a primary X-ray beam 104 with the required radiation energy, focal spot size and intensity. X-ray optics 106 are provided to condition the primary X-ray beam 104 to a conditioned, or incident, beam 108 with the required wavelength, beam focus size, beam profile and divergence. A goniometer and stage 110 are used to establish and manipulate geometric relationships between the incident X-ray beam 108, the sample 112 and the X-ray detector 114. The incident X-ray beam 108 strikes the sample 112 and produces scattered X-rays 116 which are recorded in the detector 114. A sample alignment and monitor assembly comprises a sample illuminator 118, typically a laser, that illuminates the sample 112 and a sample monitor 120, typically a video camera, which generates a video image of the sample to assist users in positioning the sample in the instrument center and monitoring the sample state and position.
The two-dimensional detector 114 intercepts and records the scattered x-rays 116 from the sample 112, and saves and displays the diffraction pattern in a two-dimensional image frame.
In the laboratory, X-ray diffractometers can be used to determine crystal structure and identify compounds. During laboratory data collection, the sample and instrument components are typically moved. For example, the gonimeter is used to provide a data scan and to set a tilt angle between the incident X-ray beam and the sample. However, there are many applications that require a diffractometer to be used outside of the laboratory. For example, with in-situ stress measurements, the diffractometer must be brought to the location of the stressed member. Consequently, a portable or handheld X-ray diffractometer would be desirable. Such a handheld instrument must be light in weight, small in size and energy efficient. Aligning the instrument accurately to the sample spot to be measured is also critical to obtain accurate measurement results. However, the conventional laboratory instrument is not suitable for handheld use because the setup is bulky and large and, as set forth above, requires that the instrument components be moved during data collection. Further, it would be difficult to properly align the instrument to the sample spot.